Conversion of Direct Current (DC) energy from one voltage to another has been a standard function in many electrical and electronic systems since at least the beginning of the twentieth century.
As used herein a dynamical electro-state (DES) denotes one or more of a voltage, a current, or an inductance of at least one node with respect to a second node in a circuit. The voltage and/or the current may be determined by measurements between the node and the second node, which may vary over time. Inductance is discussed with regards to inductors. The current may be considered the rate of change over time of the electrical charge at the node flowing to the second node. The standard units in this document are for voltage the Volt (V), for current the Ampere (Amp), and for charge Coulomb (C). Voltage is considered synonymous with potential difference herein.
Circuits may often include, but are not limited to, devices including terminals, multiple nodes, electrical connections between some, but not all, of the terminals and/or some, but not all, of the nodes. The circuit, together with its included devices and electrical connections, forms multiple DES. Each of the DES may have an electro-state that may be shared across multiple nodes with respect to a solitary second node. In other situations one or more of the DES may have an electro-state that measurably changes from one node to another node with respect to the second node.
Some of the standard devices found in circuits include, but are not limited to, a capacitor, a resistor, an inductor, a diode and/or a switch. These standard devices will now be briefly discussed in terms of the prior art.                A capacitor is typically a two terminal device whose primary electrical property is its capacitance across its terminals. Capacitance is often seen as the ability of electrical charge, and therefore electrical energy, to be stored in the device. Capacitors are often modeled and/or built as two parallel conductive plates separated by a dielectric. The capacitance is usually modeled as directly proportional to the surface areas of the conductive plates and inversely proportional to the separation distance between the plates. Capacitance is further considered to be a function of the geometry of the plates and the permittivity of the dielectric. The unit of capacitance used herein is the Farad. A one Farad capacitor, charged with one Coulomb, is defined to have a potential difference of one volt between its plates. The usual model for capacitance is C=ere0 A/d, where C is the capacitance in Farads. A is the area of overlap of the parallel plates. er is the permittivity of the dielectric. e0 is the electric constant (roughly 8.854*10−12 F/meter), and d is the separation of the plates in meters. Energy is measured in Joules (J), and when stored in the capacitor, is usually defined as the work done to charge the capacitor to its current state. The energy stored in the capacitor is often estimated as CV2/2 and reported in Joules.        An inductor is typically a two terminal device whose primary electromagnetic property is its inductance across its terminals. Inductors typically include a coil of conductive material often referred to as a wire. The wire connects the two terminals of the inductor. The wire between the terminals is often wound about an axis. In some situations, the windings are essentially symmetrical about the axis. The interior of the coil may or may not include a metallic core. Inductance is often defined as an electromagnetic property of the wire by which a change in current flowing through it induces a voltage (electromotive force), in both the wire itself (self-inductance), and in any nearby wires (mutual inductance). Inductance is often measured as the response by the coil to a time-varying, often sinusoidal, voltage of a given frequency applied across its terminals. The unit of inductance in this document is the Henry (symbolized H) a Standard International (SI) unit. Reduced to base SI units, one Henry is the equivalent of one kilogram meter squared per second squared per ampere squared (kg m2 s−2 A−2). It is common for inductors to be rated in Henries for a sinusoidal test pattern at a specified frequency, often one Kilo Herz.        A resistor is typically a two terminal device whose primary electrical property is its resistance across its terminals. Resistance is measured in units of the ohm, a SI unit. As used herein, the ohm is defined as the resistance between two nodes when a constant potential difference of one volt, applied to these nodes, produces a current of one ampere.        A diode is typically a two terminal device whose primary electrical property is that it blocks current flow from the first terminal to the second terminal, while it allows current flow from the second terminal to the first terminal with a pass resistance.        A switch refers to any one or more of the following: a mechanical switch, a solid-state switch, and/or a merged solid-state and mechanical switch. As used herein a switch includes a first and a second terminal and a control terminal. When the control terminal is in a closed state, the first and second terminals are connected, or closed. When the control terminal is in an open state, the first and second terminals are open, or unconnected.        
A system may include one or more circuits and/or one or more devices. For example, an automobile is considered a system that may include a transmission circuit operated to aid in propelling the automobile and an air conditioning device operated to aid in climate control within a passenger compartment of the automobile.
A Direct Current (DC) DES refers herein to a DES whose current flows in just one direction between the node and the second node. An Alternating Current (AC) DES refers to a DES whose current flows both from the node to the second node and from the second node to the first node over time.
As used herein, an energy transfer device will refer to a circuit that includes an input DC terminal, an output DC terminal and a common terminal, and is adapted to receive a DC DES from the input DC terminal and to generate at least one output DC DES. The input DC DES has as its first node the input DC terminal. The output DC DES has as its first node the output DC terminal. Both input and output DC DES share the common terminal as their second node.
It has been conventional wisdom for several decades to favor energy transfer devices implemented as DC-to-DC converters. These DC-to-DC converters use an inverter responding to an AC timing DES to transform a DC input DES into an AC internal power DES that drives a primary coil of a transformer. The secondary coil(s) of the transformer generate at least one secondary AC DES. The secondary AC DES is then filtered and rectified to create the output DC DES of the DC-to-DC converter. Note that some or all of the AC DESes, particularly the secondary AC DES, are often implemented by a pair of wires.